trigonometry derivative

1. Use the inequalities sinx<x<tanx for a suitable value of x to show that pi lies between 3 and 2root3.

2.By writing tanx as sinx/cosx, show that d(lntanx)/dx = 2cosec2x.

3. A tuning fork sounding A avobe middle C oscillates 440 times a second. The displacement of the tip of the tuning fork is given by 0.02cos(2pi x 440t) millimetres, where t is the time in seconds after it is activated. Find
a. the greatest speed, b. the greatest acceleration of the tip as it is oscillates.

If you know the answers to any of these questions, please, please help!
Thanks!

3. A tuning fork sounding A avobe middle C oscillates 440 times a second. The displacement of the tip of the tuning fork is given by 0.02cos(2pi x 440t) millimetres, where t is the time in seconds after it is activated. Find
a. the greatest speed, b. the greatest acceleration of the tip as it is oscillates.